A technique for mutual authentication between two authentication object apparatuses are known from, Japanese Laid-open Patent Publication No. 2015-080111, for example.
However, according to the prior art, since communication for a single mutual authentication is required at least 4 times, there is a problem that it is not efficient. Between the two authentication object apparatuses, there is a probability that a communication path other than for the mutual authentication is used, and thus it is desirable to reduce as much as possible the number of times of communication required per single mutual authentication.